Abstract

Designers increasingly recognise the need for user-centred approaches to system specification, yet the last thing they want is for yet another design method to be imposed upon them. To receive widespread use, task analysis methods must be an integrated and primary part of the design process. This chapter describes the Sub-Goal-Template (SGT) method for producing requirements specifications from task analyses. The SGT method captures a set of information requirements for each user task, and documents the commonalities and differences among tasks and task sequences under constraints of context and limits of performance. Critically, this information is specified in a form that can be used directly by clients and designers as a specification of information requirements, and even as tender and evaluation documents. A brief overview of the SGT approach to hierarchical task analysis is illustrated with an example showing the design of supervisory control systems for a simplified railway network.